1. Field of the Invention
This invention relates, generally, to bimanual rehabilitation. More specifically, it relates to a device and method for bimanual rehabilitation for persons with hemiparesis.
2. Brief Description of the Prior Art
The goal of upper-limb rehabilitation following a stroke is to enable a person to use both hands in activities of daily living. Of the new rehabilitation methods proposed and tested in recent years, many show positive results [1] [2], but there is a need for a more effective method that clearly shows better results than traditional methods. A common thread among the successful studies is that the amount of time spent training the affected arm plays an important role in improving the functional ability of the affected arm. As it is difficult for therapists to devote as much time as is needed, researchers have looked to robotic techniques, bimanual techniques, and other techniques to supplement the rehabilitation.
Traditional and Robotic Rehabilitation Techniques
Conventional stroke rehabilitation therapies, such as the Bobath method [3] and proprioceptive neuromuscular facilitation [4] have been used for decades. However, these methods are time-consuming and require significant effort from physical therapists. Forced use [5] and the more recently developed Constraint-Induced Movement Therapy [6] bind the sound arm and force the individual to use only the paretic limb; however, this therapy is only viable for small to moderate impairment.
In recent years, robotic technologies have been used to provide rehabilitation to individuals, allowing access to rehabilitation for longer and more frequent periods of time. However, recent publications have noted that it is unclear whether robotic methods have the potential to produce greater benefits than conventional techniques when practiced for the same amount of time [1] [2].
To allow patients greater access to rehabilitative training, several methods have been developed to allow patients to rehabilitate at home [7] [8]. However, many of these home-based methods use a home computer with limited accessories that cannot provide assistance forces and can only operate over a small workspace. These methods are able to provide some benefit, but the rehabilitation effect is limited to individuals already having relatively high motor function.
Bimanual Rehabilitation
Bimanual rehabilitation allows individuals with hemiparesis to use their sound arm to help rehabilitate their impaired arm through simultaneous bimanual motions. Bimanual rehabilitation shows promise as a means of low cost home use rehabilitation. The key mechanism of rehabilitation is that the same neural signal is sent to both arms, which results in the same proprioceptive feedback from each limb since the arms are constrained to move together. Sending the same efferent signals to each limb results in similar afferent signals from the limbs, which helps re-train the motor pathways to the impaired side/limb [9] [10]. Several research groups have studied certain aspects of coupled and uncoupled bimanual rehabilitation [11] [12] [13] [14] [15], but few studies have examined what the ideal physical parameters for bimanual interaction should be.
The foregoing studies [11] [12] [13] [14] [15] either did not physically connect the hands or coupled the hands rigidly, and few studies have analyzed the effect of the coupling stiffness. An effective coupling stiffness is likely an intermediate stiffness, since a soft coupling would prevent severely impaired individuals from using this training method. With a completely rigid connection, the individual is likely to apply minimal force in their impaired hand since the healthy side would dictate all the motions [1] [16].
Further, it is not currently known which types of symmetry modes are most effective for bimanual rehabilitation. Mirror motions have been the most commonly used in bimanual rehabilitation studies to date. However, most daily tasks occur in a visual reference frame where the hands move in the same direction. Three common reference frames used in bimanual rehabilitation are Mirror or Joint Space Symmetry (JSS), Visual Symmetry (VS), and Point Mirror Symmetry (PMS) [17] [18](see FIG. 1).
Preliminary studies of bimanual symmetric motions on healthy participants have shown that it is easier to follow and recreate motions in VS and JSS than in PMS [19] and that a coupling stiffness of 200 N/m or greater resulted in better path following and motion coupling. These studies were performed on a pair of PHANTOM OMNI force feedback devices.
Certain devices and methodologies for bimanual rehabilitation do exist in the art, though most use either a rigid physical coupling or a large robotic device to effect the coupling, since the best combination of bimanual symmetry modes and coupling stiffnesses is unknown. For example, U.S. Pat. No. 7,850,579 to Whitall et al. (also published as EP B1 and WO2001056662 A1) relates to a device for bilateral upper extremity training for patients with a paretic upper extremity, and more specifically, to a device providing bilateral upper extremity training that facilitates cortical remodeling. However, the bilateral arm trainer of Whitall et al. includes two separate handles on slides for each hand and the two motions are uncoupled except via the person's control, thus failing to provide physical coupling of the motions together in multiple symmetry modes.
U.S. Patent App. Pub. No. 2012/0029391 A1 to Sung et al. relates to a bilateral upper limbs motor recovery rehabilitation and evaluation system for patients with stroke. However, Sung et al. focuses on evaluating the amount of asymmetry an individual with stroke has. The system is designed to allow an individual to move bilaterally with both arms and measures the difference between the two arms and defines metrics to aid in evaluation. It does not include a semi-compliant physical connection or a method to switch between different symmetry modes.
U.S. Pat. No. 8,038,579 to Wei et al. relates to a system adapted to stroke patients for training and evaluating bilateral symmetric force output. However, the focus of Wei et al. is the force being mediated by a motor, which becomes costly and less user-intuitive for a home-user thereof.
Symmetric Motions for Bimanual Rehabilitation. Hernando Gonzalez Malabet, Rafael Alvarez Robles, and Kyle B. Reed. Oct. 18-22, 2010, Taipei, Taiwan relates to the development of bimanual rehabilitation for home-use. Although this publication is relevant to bimanual rehabilitation, it is more theoretical in nature and furthers an understanding of how people couple motions, but does not discuss a device or method for coupling the hands.
Peter S. Lum, David J. Reinkensmeyer, Member, IEEE, and Steven L. Lehman, Associate Member, IEEE. Robotic assist devices for bimanual physical therapy: preliminary experiments. IEEE transactions on rehabilitation engineering, vol. 1, no. 3 sefizmber 1993 relates to the development of a device, operating under simple control laws, to assist a disabled hand, allowing performance of coordinated bimanual tasks. However, this publication is focused on bimanual wrist actuation and would not be conducive for whole arm movements.
Peter S. Lum, Steven L. Lehman, Associate Member, IEEE, and David J. Reinkensmeyer, Member, IEEE. The bimanual lifting rehabilitator: an adaptive machine for therapy of stroke patients. IEEE transactions on rehabilitation engineering, vol. 3, no. 2, June 1995 relates to the development of inexpensive bimanual lifting rehabilitators, each designed to retrain coordination in a specific activity of daily living, which could be used by physical and occupational therapists. This paper is focused on performing motions bimanually, but not on using one hand to assist the other during a reaching task. The “rehabilitator”, rather than the person's healthy hand, assists the impaired hand, and the device enables only a limited type of rehabilitation.
Matic Trlepa, Matja{hacek over (z)} Mihelj a Ur{hacek over (s)}ka Puhb and Marko Muni. Rehabilitation Robot with Patient-Cooperative Control for Bimanual Training of Hemiparetic Subjects. Advanced Robotics: Volume 25, Issue 15, 2011 relates to the development and validation of a bimanual training system that stimulates the use of both arms of hemiparetic subjects. The adaptive assistance control adjusts the contribution of the unaffected arm, thus reducing the load on the paretic arm. This paper presents a bimanual rehabilitation method that couples the motions of both hands through an “adaptive assistance” paradigm that works by controlling how much force the sound arm can contribute to the overall motion using admittance control. The coupling in this system is effected by a rigid coupling to a robotic device, rather than a passive compliant coupling, and enables limited symmetry types.
Accordingly, what is needed is a more effective device and methodology for bimanual rehabilitation. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.